Numerical Simulation Of The Extrusion Process For Plastic Profile And Design Optimization Of Extrusion Die

Plastic profile is a plastic product with non-formula section by extrusion. It is applied in many fields, especially plastic window and door. Extrusion die has an important effect on product quality and production efficiency, so it is very important to design extrusion die accurately. The flowing velocity field in extrusion die and the cooling transient temperature field in calibrator are gained by the numerical simulation of extrusion process, and die structure optimization, which have a significant effect on design and manufacture of extrusion die. So study on the numerical simulation of extrusion process for plastic profile has important theoretic and practical meaning to the extrusion die design.In the paper, the melt three-dimensional flowing process in extrusion die is studied deeply. Aiming at wall slip problem, the idea that wall slip velocity should be loaded on the FEM boundary is presented. The measuring method of wall slip velocity is given, and a online polymer extrusion rheometer of double capillary is designed. To the complicated 3-D die cavity model, a stepwise element meshing strategy is presented. The Bird-Carreau equation is applied, and the 3-D flowing process in die is simulated. The analysis in the balance effect of die structure on multi-flow channel is carried out by orthogonal experiment and numerical simulation technology.An optimal method based on the flowing balance is presented to design the runner structure, combining the theory of polymer rheology and the optimization design theory. The objective function is the flow balance of each sub-field of product section at extrusion die exit. The example analysis and experiment show the flowing uniformity of the optimal die is improved. The proposed method has stronger adaptability and practicability by integrating finite element analysis and optimal design theory.The plastic profile cooling process in calibrator is analyzed by the heat transfer theory, and the heat transfer model is presented. The initial and boundary conditions are given those are nearer practical manufacturing, the calculation method of heat transfer coefficient between plastic profile and calibrator cavity is given, and the cooling process of plastic profile stayed at calibrator is simulated. The transient temperature field of plastic profile in the calibrator different time is gained.Lastly, the design variables are the positions of the cooling channels. The objective function is the cooling uniformity and efficiency of plastic profile in calibrator. The optimal design method of the cooling channels in calibrator based on the transient temperature field is presented. In order to solving the uneven cooling problem, the unconventional design method of the cooling channels is applied. The manufacturing practical and experiment show the profile cooling uniformity and efficiency is improved after the channels in calibrator are optimized. Using the thermal-mechanical coupling fundamental equations based on finite strained theory, a thermal-mechanical coupling calculation is carried out to the cooling process of plastic profile in calibrator. A new reverse deformation design method of calibrator cavity is put forward, and profile deformation could be mapped to cavity contour directly. The correctness and validity of the method are illustrated through an experiment.